M945 with FCO-2 sight. Note flip-up front and rear sights in “down” position.

The M945 is the standard-issue rifle of the United States Armed Forces. An updated form of the famous M16 rifle, the M945 is chambered in a new high-velocity round that is more accurate and has significantly better terminal effects than the 5.56x45mm NATO round used by older M16 models. It replaced the M5 rifle in US service.

The rifle was found to be so effective that it continued in service for over 150 years, although this was also partly due to the Future Weapons Development Ban passed in 2036. In addition, three variants, the M956 marksman rifle, the M950 heavy-barreled assault rifle, and the M933 carbine, were developed in conjunction with the M945 and serve alongside it.

Weapon Designation:Rifle, 6.2mm, M945
Type:Assault Rifle
Place of Origin:United States
Production History:
Manufacturer:Colt Defense, LLC
Weight:7.2 lb (3.27 kg)
Length:39.8 in (1,011 mm) (stock extended)
35.8 in (909 mm) (stock retracted)
Barrel Length:20 in (508 mm)
Action:Gas-operated short-stroke piston
Rate of Fire:700 rounds/min cyclic
Muzzle Velocity:3,250 ft/s (991 m/s) with M62-110 round
Muzzle Energy:2,580 ft/lbs (3,498 Joules) with M62-110 round
Effective Range:800 m (875 yd)
Feed System:30-round detachable box magazine
Sights:Optics rail (FCO-2 sight as standard)
Flip-up iron sights


With the passage of the Unified Arms Resolution in 2031, the US military was expected to adopt the M5 rifle and M250 automatic rifle across all five primary branches. However, this was met with significant resistance due to issues with the M5 and M250 that were discovered during field use in the mid- and late 2020s, and the US Marine Corps flat-out refused to accept either design. After much controversy and several Congressional hearings, the five branches were ordered to come to an agreement on a family of new designs to fill rifle, carbine, automatic rifle, and marksman rifle roles.

The first design proposals were accepted for tests in 2034. Proposals were required to focus on maximum effectiveness and parts commonality at minimum cost, necessitating a much simpler design than previous weapons like the M5 and M250. Although companies like Colt, Daniel Defense, Heckler and Koch, and FN Herstal all submitted designs, the contest was won by the Future Small Arms System, a family of weapons designed by Kinman Industries, a small firearms manufacturing company based in Tennessee. The Future Small Arms System was adopted to replace a wide variety of weapons in the US military, including the M5 rifle, M250 automatic rifle, M110A1 marksman rifle, M4A1 carbine, Mk14 and Mk 20 rifles, and the M249 squad automatic weapon.

Kinman Industries’ rifle member of the family was accepted as the M945 rifle in late 2034, while the carbine was adopted as the M933, the heavy automatic rifle as the M950, and the marksman rifle as the M956. Despite winning the contest, Kinman lacked full-scale production facilities; this led to a production license being sold to Colt Defense, which took over the majority of production of the M945 for the military. Kinman produced some military M945s but largely focused on law enforcement sales of the M945 and a semiautomatic version of the rifle, designated the AR-945, for the civilian market. Following the passage of the Colonial Militia Act and the repeal of the 1986 Hughes Amendment in 2063, allowing civilian purchase of new automatic weapons, Kinman discontinued the AR-945 and began selling the M945 on the civilian market instead.


The M945 is a very simple design, and is essentially an upgraded M16A3 with a free-floating barrel and short-stroke gas piston. At a time when the military was coming under fire for encouraging the use of large numbers of weapon-mounted accessories, many of which proved less successful than hoped under combat conditions, the M945 focuses on maximum simplicity. While it can be used with a quad-rail handguard similar to that used by the M16A4, it is typically used with a round, ribbed handguard based on the M16A2. However, despite the similarities in appearance to the M16-type handguards, both the round and quad-rail handguards are in fact free-floating, and the mount at the front of the handguard that looks like a conventional gas block is in fact a part of the free-floating handguard. The actual gas block is a low-profile block under the handguard, while the gas system itself uses a short-stroke piston instead of direct impingement. This increases recoil slightly but keeps the rifle much cleaner, which improves reliability and maintenance.

The M945 is considered a “partially ambidextrous” rifle; while the safety is fully ambidextrous, the magazine release and bolt catch release are less convenient for left-handed shooters to use, but still reasonably easy with practice. Although based on the M16, the M945 uses the M4-type collapsing stock. The casing deflector on the right side of the receiver has been reshaped, reinforced, and now also houses a rearward-facing LED display that shows how much ammunition is left in the magazine. The display can be dimmed for night operations or even shut off entirely. Unlike the display on the M41, the M16A5P’s display is pointed backwards towards the operator so that it can be more easily viewed by right-handed users, and the display screen and numbers are much smaller. The “button-type” battery that powers this screen is in the casing deflector and can be easily replaced in the field by removing the screen to access the battery.


The 20-inch barrel is constructed of a proprietary steel-carbon-stellite alloy, making it exceptionally wear-resistant. It has 1:10 right-hand six-groove rifling to adequately stabilize the 110-grain M62-110 round used by the rifle. Although the long barrel has brought some criticism because of the resulting overall length of the rifle, the increase in effective range is widely considered to be more than sufficient justification for the greater length. Many units will retain large quantities of complete M933 carbine upper receivers in their armories, allowing most or all of their M945s to be converted to M933s very quickly before deployment for urban or other close-quarters combat. Although this comes with additional complications for maintenance and supply, it largely alleviates the length issue and is an officially approved system for improving personnel maneuverability and ease of operation in confined spaces.

Muzzle Devices:

The M945 can be equipped with various muzzle devices for different roles. The most common is a muzzle brake based on Precision Armament’s “Hypertap Muzzle Brake” for the AR-15, which reduces felt recoil by a full 83 percent. This makes the M945 extremely comfortable to fire, to the point that it has less recoil than even a standard M16 in 5.56x45mm NATO. Smith Enterprise, Inc. makes a version of its Vortex Flash Hider which almost entirely eliminates all muzzle flash, as an alternative to the muzzle brake, while a third offering is a suppressor designed and built by Griffin Armament.


The M945P is equipped with a pair of flip-up iron sights, but it is primarily intended to be used with the FCO-2 optical sight mounted on the optics rail on the top of the upper receiver. The Fire Control Optic 2 is a follow-on to the M157 Fire Control Optic used on the M5 and M250 rifles that improves durability, reliability, battery life, and ease of use compared to the M157. In addition to a thermal imaging mode and wireless helmet-mounted display connection, the FCO-2 has all of the features of the M157, including the ability to still be used as a regular optic in the event of power loss or electronic failure. This makes it well-liked by users, because even if the electronic functions become inoperable in the field, the scope does not become “dead weight”.

Range, Accuracy, and Terminal Ballistics:

The M845 is widely regarded as an exceptionally accurate rifle, with its standard issue ammunition, the M62-110 round obtaining a 95% hit rate on an 8×8-target at 600 meters. When combined with the FCO-2 optic, the M945 is officially listed as being accurate out to 800 meters, although many troops have reported making kills at or over 1,000 meters.

Terminal effects for the 6.2x48mm round are greatly improved over the 5.56x45mm NATO round. The 110-grain bullet used by the cartridge is a fluted design machined from copper with a steel core insert. The fluted design gives the bullet devastating effects in soft tissue while the steel core makes it capable of penetrating many types of body armor similar to the 6.8x51mm Common round used by the M5 and M250, although the 6.2x48mm has increased effect in soft tissue, less recoil, and higher muzzle velocity at the cost of slightly less bullet energy.

Additional Accessories

The M945 is meant for use with the M10 bayonet, which serves as a multi-purpose bayonet, fighting knife, and utility tool. It can also mount the M523 under-barrel grenade launcher and the M352 underbarrel shotgun.

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